Recent content by Jennifer_ea

  1. J

    Using given Fourier transform to find the equation for the wave packet.

    Wow, I was so focused on trying to figure out what the transform did that I completely overlooked the basics. Did not cross my mind once about the omega disappearing. Thanks a bunch! You're right, it's just simple substitution now. Lesson learned!
  2. J

    Using given Fourier transform to find the equation for the wave packet.

    Homework Statement Any wavepacket can be obtained by the superposition of an infinite number of plane waves using the so-called Fourier integral or Fourier transform f(x,t) = \frac{1}{\sqrt{2\pi}} _{-\infty}\int^\infty A(k)e^{i(kx-\omega t)} dk Find at t=0 the representation of the...
  3. J

    What Is the Efficiency of a Refrigerator with a COP of 13.8?

    ack! Thank-you so much, that was the push I needed
  4. J

    What Is the Efficiency of a Refrigerator with a COP of 13.8?

    Homework Statement The question is simply: A reversible refrigerator has a coefficient of performance equal to 13.8. What is its efficiency? Homework Equations COPrefrigerator = Tc/(Th - Tc) Efficiency = (Th - Tc) / Th The Attempt at a Solution I'm assuming I need to use these equations to...
  5. J

    Percent change in tension to achieve specified change in frequency

    Oops, didn't notice that option! Yup, I knew this would be a face palmer. When doing the logic out I knew it had to decrease but somehow deemed the negative unwarranted. Thanks a million!
  6. J

    Percent change in tension to achieve specified change in frequency

    % change in tension to achieve specified change in frequency Homework Statement A particular guitar string is supposed to vibrate at 219 Hz, but it is measured to actually vibrate at 224 Hz. By what percentage should the tension in the string be changed to get the frequency to the correct...
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